This invention relates generally to warehouse cranes with a vertically movable carriage for retrieving tote pans from individual storage areas along an aisle. In particular, it relates to an improved tote pan engaging means, the improvement comprising a pair of vertically stationary pins on two elongated orbits.
Tote pan pullers are generally known in the art and include many different configurations including those with pin-type pullers mounted on a chain. For example, in U.S. Pat. No. 4,010,855, issued to Smith on Mar. 8, 1977, has a plurality of pins mounted on a rotating chain to engage tote pan handles, each chain having a long and two short pins. The handles are attached to the aisle-facing sides of the tote pans and are of a generally inverted U-shape, the lower end of the handle ending at a point well above the height of the bottom of the pan. After the pan has been placed upon the vertically-movable carriage, the smaller pins move towards its handle-engaging side. The short pins do not engage any portion of the handle, but pass under it, engaging the side of the tote pan to push the pan into the desired storage area at a proper depth for retrieval during a subsequent operating cycle. If the vertical position of the shorter pins with respect to the handle were changed so as to enable those shorter pins to engage the outer portion of the handle, the short pins would push the tote pan and its handle farther into the storage area than is desired, which could make the pan subsequently irretrievable.
Several other tote pan pullers are disclosed in the art, including those described in U.S. Pat. No. 4,007,846, issued to Pipes on Feb. 15, 1977, and U.S. Pat. No. 3,883,008, issued to Castaldi, on May 13, 1975. Pipes discloses an apparatus having a pair of fingers vertically movable to engage the pan handle, each of the fingers moving the pan about half the distance from the position in which the pan is fully contained with the storage area to the position in which the pan is centered upon the carriage. The operation of such a tote pan puller requires the cooperation of several limit switches, solenoids, clutches, and spring-biased mechanical elements, and is thus rather complex and subject to undesirably frequent failure due to mechanical or electrical malfunction.
Castaldi discloses an apparatus enabling retrieval or return of pans with a slide movable towards and away from the pans. The slide is positioned between a pair of endless belts and moves on elongated means and in a path parallel to the length of those belts. Each of the pans has handles for enabling removal of the pans from the storage areas or bin locations by two similar pins. The pins are normally in a horizontal position and below a horizontal plane including the upper surface of the belts, and thus the horizontally-disposed pins do not engage the handle and cannot move the pan from the bin location. Upon actuation of a solenoid, the pins are either vertically erected to extract the pan from its bin location by engaging the included space between the handle and the body of the pan, vertically erected prior to the slide reaching its extreme rightward or leftward position so that the pin will be poised to engaged the outer surface of the handle and thereby permit replacement of the pan at its proper location in the bin. The many relays, solenoids, and limit switches necessary to determine when a pin must be raised or lowered subject this apparatus to the same kinds of mechanically-and electrically-based vulnerabilities as Pipes. In addition, both Pipes and Castaldi require that pans of very consistent, reproduceable lengths be used to ensure that the vertically movable pins will engage the included space between the handle and the side of the tote pan rather than the underside of the pan or the lower lip of the U-shaped handle.
In addition, existing tote pan pullers have rather complicated drive systems for their tote pan-engaging fingers or pins, necessitating many adjustments to ensure tightness in the chains of the drives or to make a phase adjustment in the pin cycle and to thereby ensure the synchronous movement of those pins.